Protein-glycosaminoglycan interactions: infectiological aspects

Glycosaminoglycans (GAGs) are linear heteropolysaccharides consisting of repeated disaccharide units that are variablyN- andO-sulfated. Due to this heterogeneity, GAGs possess a high amount of structural information. Linked to a protein core to form a proteoglycan, GAGs are present on the surface of probably all mammalian tissues. During the recent years, a number of pathogens ranging from viruses to protozoans were found to interact specifically with cell surface GAGs to recognize and bind to their target cells. This review is intended to give a short overview over protein-GAG interaction under the aspects of infection.     

牛主动脉蛋白聚糖对培养的人主动脉平滑肌细胞生长的影响

为探讨蛋白聚糖在动脉粥样硬化发生发展中的作用,观察牛主动脉硫酸肝素蛋白聚糖、硫酸软骨素蛋白聚糖、硫酸皮肤－硫酸软骨素蛋白聚糖和三种蛋白聚糖的混合物对培养的人主动脉平滑肌细胞增殖的影响。用细胞计数计算硫酸肝素蛋白聚糖（１．５￣７．０ｍｇ／Ｌ）对培养的人主动脉平滑肌细胞增殖的抑制率分别为０．５５％和７６％;硫酸软骨素蛋白聚糖（１５．０￣６０．０ｍｇ／Ｌ）的抑制率分别为２３％、３４％和６５％;硫酸皮肤素     

儿童股骨头坏死患髋软骨蛋白多糖及滑液血清透明质酸的生物化学研究

目的研究股骨头坏死患儿患髋的生物化学改变,分析关节功能状态在疾病中所起的作用。方法本实验运用放射免疫学方法检测了２０例儿童股骨头坏死患髓软骨,１０例与患儿年龄相当的尸体同部位软骨的蛋白多糖（ＰＧ）三组份：氨基己糖、己糖醛酸、硫酸基含量和患儿关节腔液及外周血清透明质酸（ＨＡ）含量,并分别与正常对照组相比较,同时分析软骨ＰＧ、关节腔液和血清ＨＡ三者相互之间的相关性。结果①儿童股骨头坏死患儿软骨ＰＧ三组份含量较正常对照明显下降（Ｐ＜０．０１）;②股骨头坏死患儿血清ＨＡ浓度明显高于正常对照组（Ｐ＜０．０１）,关节腔液ＨＡ与血清ＨＡ呈负相关（ｒ＝－０．６６３,Ｐ＜０．０５）;③股骨头坏死患儿关节腔液ＨＡ浓度与软骨ＰＧ含量均呈正相关（ｒ＝０．６８２,Ｐ＜０．０５）;软骨ＰＧ含量与血清ＨＡ浓度呈负相关（ｒ＝－０．６３２,Ｐ＜０．０５）。结论①儿童股骨头坏死患髓关节功能有明显障碍;②血清ＨＡ对于儿童股骨头坏死病可在一定程度上反映软骨功能状态;③关节功能障碍与股骨头坏死病变相互促进,恶性循环。     

钌红电镜组织化学技术应用

目的 采用钌红电镜组织化学技术对涎腺多形性腺瘤，肌上皮瘤，腺样囊性癌和基底细胞瘤进行研究以示踪肿瘤中蛋白多糖的形成和分布。方法 新鲜标本分切后固定于2.5%戊二醛中24小时，其中含0.2%的钌红；0.1M二甲肿酸钠缓冲液冲洗过夜；1%OsO4后固定1小时；丙酮逐级脱水，Epon812包埋，在半薄切片上定位，超薄切片用Opton109型电镜观察，结果 在多形性腺瘤和肌上皮瘤中，粘液样区域内充满了蛋白多糖，这种蛋白多糖是由NMCs分泌产生的，腺样囊性癌的NMCs也分泌产生蛋白多糖，该瘤中筛状结构形成是由于NMCs分泌蛋白多糖所致，这种分泌功能的出现是肌上皮细胞向肿瘤性细胞转变的一个标志。结论 钌红电镜组织化学技术方法可检涎腺肿瘤中蛋白多糖形成和分布，是一种简便，易行的方法。     

Age matters: collagen birefringence of superficial articular cartilage is increased in young guinea-pigs but decreased in older animals after identical physiological type of joint loading

OBJECTIVE: To compare responses of the collagen network and glycosaminoglycans (GAGs) of articular cartilage to physiological type of joint loading in young growing and adult mature guinea-pigs. DESIGN: 10- and 44-week-old guinea-pigs were accustomed to treadmill running for 3 weeks. Thereafter the animals ran 2500 m/day, 5 days a week, for 15 weeks. Articular cartilage specimens from knee joints were collected at 28 and 62 weeks. Osteoarthritis (OA) prevalence and severity was evaluated by aid of light microscopy. The degree of collagen fibril network organization and content was analyzed with quantitative polarized light microscopy. The local concentration of GAGs was determined from cartilage sections with digital densitometry after safranin-O staining. RESULTS: In the young guinea-pigs, running increased up to 24% the optical retardation of polarized light by collagen in the superficial articular cartilage of femur, indicating either a higher degree of fibril assembly and organization or increased amount of collagen, or both. In contrast, in the adult mature animals the optical retardation decreased almost 50% after joint loading (P< 0.01-0.001). Running did not increase cartilage fibrillation. Significant changes in GAG content of cartilage were not found either in the young or adult mature runners. CONCLUSIONS: Increased birefringence of the superficial articular cartilage after joint loading in young guinea-pigs can be interpreted to be a sign of improved and decreased birefringence in older animals a sign of worsened property of the collagen network. It can be suggested therefore that joint loading strengthened the collagen network in the young runners. It can be hypothesized further that with time the inferior property of the collagen network predisposes the older runners to earlier OA than in controls.     

Canine osteoarthritis: Effects of endogenous neutral metalloproteoglycanases on articular cartilage proteoglycans

The aim of this study was to analyze the mechanisms by which neutral metalloproteoglycanases (NMPE) degrade proteoglycans (PGs) in the cartilage of an experimental model of osteoarthritis (OA). We demonstrated that chondrocytes in osteoarthritic cartilage synthesize PGs with the same functional characteristics as those found in normal cartilage. Osteoarthritic cartilage contains NMPE in both active and latent forms. Both forms can degrade newly synthesized and endogenous PG macromolecules, as indicated by the reduced hydrodynamic size found in the two PG populations of osteoarthritic cartilage. PG monomers, derived from the included fraction of Sepharose CL2B chromatography, were unable to form aggregates with hyaluronic acid. Reduction and alkylation showed that PG monomers from osteoarthritic cartilage had a small hydrodynamic size, especially after activation with aminophenylmercuric acetate. No significant differences were observed in the size of the chondroitin sulfate chain when normal cartilage was compared with its osteoarthritic equivalent. These results suggest that the proteolytic degradation of cartilage matrix PGs by NMPE occurs at both the hyaluronate-binding region and at the chondroitin sulfate-rich region of the core protein.     

Swelling of articular cartilage and other connective tissues: electromechanochemical forces

We have measured the relationship between tissue swelling stress and consolidation for bovine articular cartilage and corneal stroma in uniaxial confined compression as a function of bath ionic strength. Our experimental protocol and results clearly demonstrate that two concentration-dependent material properties are necessary to describe the chemical dependence of tissue swelling stress in uniaxial compression over the range of deformations and concentrations explored. A general electromechanochemical model for the swelling stress of charged connective tissues is developed. The model focuses on the role of charged matrix macromolecules in determining the mechanical behavior of the tissue. A constitutive relation for the swelling stress in uniaxial confined compression is formulated and the concentration dependence of the material properties of articular cartilage and corneal stroma is determined. The associated free swelling behavior of cartilage and cornea specimens is computed from these results and is found to compare favorably with data from the literature.     

Acute and long-lasting changes in extracellular-matrix chondroitin-sulphate proteoglycans induced by injection of chondroitinase ABC in the adult rat brain

Lattice-like perineuronal accumulations of extracellular-matrix proteoglycans have been shown to develop during postnatal maturation and to persist throughout life as perineuronal nets (PNs) in many brain regions. However, the dynamics of their reorganization in adults are as yet unknown. The aim of the present study was to examine the capability of PNs for reconstitution after experimental destruction and to search for possible consequences of extracellular-matrix degradation for neurons and glial cells. The changes were induced by single intracortical injections of Proteus vulgaris chondroitinase ABC and studied after postinjection periods of 1 day to 5 months. The N-acetylgalactosamine-binding Wisteria floribunda agglutinin (WFA), an antibody against chondroitin-sulphate proteoglycans, three antibodies recognizing initial chondroitin or chondroitin-sulphate moieties (’stubs’) of proteoglycan core proteins, an antibody against the hyaluronan-binding protein component of versican, and biotinylated hyaluronectin, which binds to hyaluronan, were used as cytochemical markers. One day postinjection, the WFA-binding sites and hyaluronan were shown to be almost completely removed within a circumscribed digestion zone. The staining of different core-protein components revealed only fragments of PNs. These changes were found to be partly compensated 4 weeks after injection of chondroitinase ABC. After 8 and 12 weeks postinjection, the cytochemical and structural characteristics as well as the area-specific distribution patterns of PNs were progressively reconstituted. At 5 months postinjection, they could not be distinguished from those in untreated tissue. In contrast to such transient changes, a diffuse chondroitin-sulphate proteoglycan immunoreactivity persisted in the neuropil. Loss of neurons or alterations of their structure as well as reactions of glial cells were not observed. We conclude from this study that PNs, enzymatically destroyed in the adult rat brain, can be completely reconstituted, but the restoration of their extracellular-matrix components needs several months. Received: 16 December 1997 / Accepted: 17 February 1998